redford case study for fan performance
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AABC Commissioning GroupAIA Provider Number 50111116
Case Study of Fan Performance
Course Number: CXENERGY1932
Neil RedfordEngineered Air Balance Co., Inc.
April 16, 2019
Credit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon request.
This course is registered with AIA
CES for continuing professional
education. As such, it does not
include content that may be
deemed or construed to be an
approval or endorsement by the
AIA of any material of construction
or any method or manner of
handling, using, distributing, or dealing in any material or product._______________________________________
Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.
This presentation is protected by US and International Copyright laws. Reproduction, distribution, display and use of the presentation without written
permission of the speaker is prohibited.
© Engineered Air Balance Co., Inc. 2019
Copyright Materials
This presentation will focus on a fan system that did not perform as
designed due to equipment and installation deficiencies. The
methods of testing and verification of measurements will be
discussed as well as system effect on the fans. The equipment
issues found stemmed from modifications made to the fan to use
316 Stainless Steel as the required material. The fan issues could
not be resolved until an aluminum fan was installed for comparative
testing.
CourseDescription
LearningObjectives
1. How system effect can be measured in the field.
2. The importance of recognizing and reducing system effect.
3. Potential impact of fan manufacturer’s assuming one wheel testing is the
same for all wheels the same size.
4. How a controlled testing environment must be maintained to identify
different variables.
At the end of the this course, participants will be able to:
System InformationTwo redundant exhaust fans serve a research facility.
VAV System
System Information
System Total Airflow Design
25,000 CFM
Fan Selection Point
• 25,000 CFM
• 3.9” WC
• 1070 RPM and 55 Hz
Wind Study required(plume height and dilution rate)
24,000 CFM
ChallengesCHALLENGES
AHEAD
All pressure independent control valves calibrated.
Independently, each fan was unable to satisfy the system.
The system required 3.5 IWC at fan inlet to satisfy
all terminal unit setpoints.
Challenge Results
Both fans were traversed and measured:
• 23,065 CFM
• 2.10” SP
• 60 Hz or 1170 RPM
Results did not match the fan curve:
• Airflow
• Static
• RPM
Challenge Fan CurveFan Curve Showing 60Hz Test Results
55 Hz Design Point
60 Hz Fan Curve Operating Point
60 Hz Actual Operating Point
X - Axis
Y - Axis
Fan CurveSystem Curve
Brainstorming Solutions
1. Are the measurements accurate?
2. Would increasing the fan speed provide the needed capacity?
3. What is causing the fan to not operate on the fan curve?
• External System Effect
• Internal System Effect
Increasing Fan Speed
Maximum Fan Speed
1334 RPM ≈ 67 Hz
The increased fan speed produced
24,145 CFM at 2.9” SP
Increasing fan speed did not
address System Effect.
Increasing Fan SpeedFan Curve Showing 67Hz Test Results
55 Hz Design Point
67 Hz Fan Curve Operating Point
67 Hz Actual Operating Point
Brainstorming Solutions
1. Are the measurements accurate?
2. Would increasing the fan speed provided the needed capacity?
3. What is causing the fan to not operate on the fan curve?
• External System Effect
• Internal System Effect
System Effect60Hz Fan Curve
55 Hz Design Point
60 Hz Fan Curve Operating Point
60 Hz Actual Operating Point
System Effect
System EffectDuct Connections
System Effect External
Manufacturer Product Data
• Maximum allowable contracting duct angle = 15 degrees
1st modification to eliminate system effect = Adjust Inlet Cone
15°
System EffectExternal
Old Inlet New Inlet
Step in the right direction but not a complete solution.
System Effect Internal
1. Could the construction of the fan be
causing system effect?
2. What difference does 316 Stainless Steel
make when building the fan?
System EffectInternal
Fan Wheel Supports Inlet Cone Construction
System Effect Fan Wheel
Inlet Cone
Supports
System Effect - Fan Wheel Supports
Inlet Cone
Inlet Cone
Fan Blades
Inlet Cone
Construction Materials
1. External sources of system effect have been minimized.
2. System effect must be caused by something internal to the 316SS fan.
3. Temporary factory tested aluminum fan was provided to replace the 316SS fan.
4. Aluminum fan successfully achieved the design capacity for both:
• Airflow
• Static Pressure
Construction Materials
55 Hz Aluminum Fan Operating Point
60 Hz 316 SS Operating Point
Controlled Environment Testing
• Stainless Steel fan tested on the test stand:
Made it possible to measure capacity with various static restrictions.
• Ability to determine the cause:
System effect was caused by the fan.
• Manufacturer identified the inlet cone was not built per design:
Different Material and Construction methods caused the
system effect.
• New Fan was re-tested on the bench:
Success; it performed as desired.
Repaired Fan Performance
55 Hz Design Point
60 Hz Fan Curve Operating Point
60 Hz Actual Operating Point
✓✓✓
Fan Curve Cause and Effect
Not every manufactured fan is tested in the factory
Construction Materials
Assuming different materials will work interchangeably
Causes Significant Problems
010000
2000030000
4000050000
60000
Carbon Steel
316 StainlessSteel
Yield Strength PSI
Material Properties
Product Verification
Verify Product Delivery
Dramatization - Not an actual fan
Controlled Testing
Controlled Environment testing made it possible
to determine the cause of system effect.
Learning Objectives Overview
1. How system effect can be measured in the field.
• Using the Fan Curve
2. The importance of recognizing and reducing system effect.
• External and Internal components
3. Potential impact of fan manufacturer’s assuming one wheel testing
is the same for all wheels the same size.
• 316 SS vs. Carbon Steel
4. How a controlled testing environment must be maintained to
identify different variables.
• Identify the deficient component
✓
✓
✓
✓
This concludes The American Institute of Architects Continuing Education Systems Course
© Engineered Air Balance Co., Inc. 2019
281-873-7084
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